Methods and Assemblies for Separating Liquid from a Gas-Liquid Stream

ABSTRACT

A two stage gas-liquid separator assembly includes a housing having an inlet for receiving a gas-liquid stream and an outlet for discharging a gas stream. A first plenum chamber includes a pre-separator that causes liquid to separate from the gas-liquid stream and to drain to a lower portion of the first plenum chamber. A second plenum chamber includes a main separator downstream of the pre-separator that further causes liquid to separate from the gas-liquid stream and to drain to a lower portion of the second plenum chamber. A first drain port drains liquid from the lower portion of the first plenum chamber and a second drain port drains liquid from the lower portion of the second plenum chamber. Liquid drains from the first and second plenum chambers regardless of a pressure difference between a pressure in the first plenum chamber and a pressure in the second plenum chamber.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of and priority to U.S. ProvisionalApplication Ser. No. 61/677,525, filed Jul. 31, 2012, the disclosure ofwhich is hereby incorporated by reference in its entirety.

FIELD

The present disclosure relates to two-stage gas-liquid separators andmethods for separating liquids from a gas-liquid stream.

BACKGROUND

U.S. Pat. No. 7,870,850, which is hereby incorporated by reference inits entirety, discloses a crankcase ventilation system for an internalcombustion engine that has a jet pump suctioning scavenged separated oilfrom the oil outlet of an air/oil separator and pumping same to thecrankcase.

U.S. Pat. No. 7,614,390, which is hereby incorporated by reference inits entirety, discloses a two stage drainage gas-liquid separatorassembly including an inertial gas-liquid impactor separator haying oneor more nozzles accelerating a gas-liquid stream therethrough, and aninertial impactor in the path of the accelerated gas-liquid stream andcausing liquid particle separation from the gas-liquid stream. Theseparator assembly further includes a coalescer filter downstream of theinertial gas-liquid impactor separator and effecting further liquidparticle separation, and coalescing separated liquid particles.

U.S. Pat. No. 6,290,738, which is hereby incorporated by reference inits entirety, discloses an inertial gas-liquid separator. A housing hasan inlet for receiving a gas-liquid stream and an outlet for discharginga gas stream. A nozzle structure in the housing has a plurality ofnozzles receiving the gas-liquid stream from the inlet, and acceleratingthe gas-liquid stream through the nozzles. An inertial collector in thehousing in the path of the accelerated gas-liquid stream causes a sharpdirectional change thereof and in preferred form has a rough porouscollection surface causing liquid particle separation from thegas-liquid stream of smaller size liquid particles than a smoothnon-porous impactor impingement surface and without the sharp cut-offsize of the latter, to improve over all separation efficiency includingfor smaller liquid particles. Various housing configurations andgeometries are provided.

SUMMARY

This Summary is provided to introduce a selection of concepts that arefurther described below in the Detailed Description. This Summary is notintended to identify key or essential features of the claimed subjectmatter, nor is it intended to be used as an aid in limiting the scope ofthe claimed subject matter.

The present disclosure is directed to a two-stage gas-liquid separatorassembly comprising a housing having a flowpath therethrough fromupstream to downstream, the housing having an inlet for receiving agas-liquid stream and an outlet for discharging a gas stream. A firstplenum chamber is defined by the housing and comprises a pre-separatorthat causes liquid to separate from the gas-liquid stream and to drainto a lower portion of the first plenum chamber. A second plenum chamberis defined by the housing and comprises a main separator downstream ofthe pre-separator that further causes liquid to separate from thegas-liquid stream and to drain to a lower portion of the second plenumchamber. A first drain port in the housing drains liquid from the lowerportion of the first plenum chamber and a second drain port in thehousing drains liquid from the lower portion of the second plenumchamber. Liquid drains from the lower portions of the first and secondplenum chambers through the first and second drain ports, respectively,regardless of a pressure difference between a pressure in the firstplenum chamber and a pressure in the second plenum chamber.

Also disclosed is a method for separating liquid from a gas-liquidstream. The method comprises: introducing the gas-liquid stream into ahousing having a flowpath therethrough from upstream to downstream. Themethod further comprises separating liquid from the gas-liquid stream ina first plenum chamber defined by the housing and draining liquid to alower portion of the first plenum chamber and through a first drainport. The method further comprises further separating liquid from thegas-liquid stream in a second plenum chamber defined by the housing anddownstream of the first plenum chamber and draining liquid to a lowerportion of the second plenum chamber and through a second drain port.The method further comprises pumping liquid from the lower portions ofthe first and second plenum chambers through the first and second drainports, respectively.

An assembly for removing scavenged liquid from a two-stage gas-liquidseparator is also disclosed. The assembly comprises a first suction portreceiving scavenged liquid from a first stage of the gas-liquidseparator and a second suction port receiving scavenged liquid from asecond stage of the gas-liquid separator. A first jet orificeaccelerates a pressurized fluid into the first suction port. A secondjet orifice accelerates the pressurized fluid into the second suctionport. A feed bore supplies both the first and second jet orifices withthe pressurized fluid. A common mixing bore receives the pressurizedfluid from the first and second jet orifices and receives scavengedliquid from the first and second stages of the gas-liquid separator.

BRIEF DESCRIPTION OF THE DRAWINGS

Examples of assemblies and methods for use with a crankcase ventilationunit are described with reference to the following Figures. The samenumbers are used throughout the Figures to reference like features andlike components.

FIG. 1 is a schematic representation of one embodiment of a crankcaseventilation system;

FIG. 2 illustrates one embodiment of a two-stage gas-liquid separator,in one embodiment, for use in a crankcase ventilation system;

FIG. 3 illustrates a flowpath through the gas-liquid separator of FIG. 2when viewed from an opposite side than in FIG. 2;

FIGS. 4 and S show sectional views through the gas-liquid separator ofFIGS. 2 and 3, wherein FIG. 4 is a top view and FIG. 5 is a bottom view;

FIG. 6 illustrates a detail view of a lower portion of the gas-liquidseparator;

FIG. 7 illustrates a sectional detail view of the lower portion of thegas-liquid separator and one embodiment of a jet pump for use with thegas-liquid separator;

FIG. 8 illustrates a top sectional view of the jet pump;

FIG. 9 is a schematic representation of flow through a jet pump;

FIG. 10 illustrates another embodiment of a two-stage gas-liquidseparator; and

FIG. 11 is a schematic representation of another embodiment of acrankcase ventilation system.

FIG. 12 depicts one embodiment of a method for separating liquid from agas-liquid stream according to the present disclosure.

DETAILED DESCRIPTION

Crankcase ventilation systems are used in conjunction with internalcombustion engines that generate blowby gas in a crankcase containingengine oil and oil aerosol. A gas-liquid separator, or an aerosol-oil orair-oil separator, has an inlet receiving blowby gas and oil aerosolfrom the crankcase. An air outlet discharges clean blowby gas to theatmosphere or back to the engine air intake. An oil outlet dischargesscavenged separated oil back to the crankcase. The gas-liquid separatorhas a pressure drop thereacross such that the pressure at its inlet andin the crankcase is higher than the pressure at its air outlet and oiloutlet. The pressure differential between the crankcase and the oiloutlet of the separator can cause back flow of oil from the higherpressure crankcase to the lower pressure oil outlet. Further, dependingon the location of venting of the crankcase ventilation system, a highvolume of liquid entering the gas-liquid separator may be present.

According to the present disclosure, FIG. 1 illustrates a crankcaseventilation system .10 for an internal combustion engine 12 generatingblowby gas in a crankcase 14 containing engine oil 16 and oil aerosol.The system 10 includes a gas-liquid separator 18, such as an air-oilseparator, having an inlet 20 receiving blowby gas and oil aerosol fromthe crankcase 14 (shown by arrow 21) and having an air outlet 22discharging clean blowby gas to the atmosphere (shown by arrow 23) orreturning clean blowby gas to the engine air intake (see FIG. 11). Thegas-liquid separator 18 further includes an oil outlet 24 dischargingscavenged separated oil back to the crankcase 14, as will be furtherdescribed herein below.

The system 10 further includes a jet pump 26 pumping scavenged separatedoil from oil outlet 24 back to crankcase 14. The engine 12 includes anoil circulation system 28 circulating engine oil 16 from crankcase 14through an oil pump 30. The oil pump 30 delivers pressurized oil throughfilter 32 to selected engine components such as a piston 34 and acrankshaft 36, and then back to crankcase 14. Pressurized oil is alsodelivered through filter 32 to jet pump 26.

Now with reference to FIG. 2, one embodiment of a gas-liquid separator18 will be described, The gas-liquid separator 18 comprises a housing 38haying a flowpath therethrough from upstream (at inlet 20) to downstream(at outlet 22). The housing has an inlet 20 for receiving a gas-liquidstream and an outlet 22 for discharging a gas stream. The housing 38comprises a first plenum chamber 40 defined by the housing 38 andcomprising a pre-separator 41 that causes liquid to separate from thegas-liquid stream and to drain to a lower portion 42 of the first plenumchamber 40. The gas-liquid separator 18 further comprises a secondplenum chamber 44 defined by the housing 38 and comprising a mainseparator 43 downstream of the pre-separator 41 that further causesliquid to separate from the vas-liquid stream and to drain to a lowerportion 46 of the second plenum chamber 44.

FIG. 3 shows flow through the gas-liquid separator 18. The gas-liquidstream enters the housing 38 at the inlet .20 as shown at arrow 48. Thegas-liquid stream is then routed through the pre-separator 41, forexample a cyclone separator as shown herein and further described hereinbelow, that causes liquid to separate from the gas-liquid stream as itis guided through the housing 38 as shown at arrows 50. Some liquid isseparated from the gas-liquid stream in the pre-separator, and thepre-separated gas-liquid stream then enters the second plenum chamber 44as shown at the arrow 52. The second plenum chamber 44 comprises a mainseparator 43, for example an impactor separator as shown herein, andfurther described herein below. The gas-liquid stream is acceleratedthrough the impactor separator as shown at arrows 54 and then exits theimpactor separator as shown at arrows 56. The gas stream then exits thehousing 38 via the outlet 22 as shown at arrow 58. According to thepresent disclosure, separated liquid drains from the housing 38 as shownat arrows 60 and 62, and further described herein below. A first drainport 64 in the housing 38 drains liquid from the lower portion 42 of thefirst plenum chamber 40. A second drain port 66 in the housing 38 drainsliquid from the lower portion 46 of the second plenum chamber 44. Liquiddrains from the lower portions 42, 46 of the first and second plenumchambers 40, 44, respectively, through the first and second drain ports64, 66 regardless of a pressure difference between a pressure in thefirst plenum chamber 40 and a pressure in the second plenum chamber 44,as further described herein below.

With respect to each of FIGS. 2-6, in the embodiment shown therein, thepre-separator 41 is a cyclone separator, but the pre-separator 41 couldcomprise various other types of gas-liquid separators. Air enters theinlet 20 tangentially as shown at arrow 48, is directed around a baffle94, and is guided around a curve defined by the inner surface 110 of thehousing 38 as shown by arrows 50. The baffle 94 minimizes pressure dropas air enters the housing 38. Air is somewhat guided by a chimney 96supported by the housing 38 and extending from the first plenum chamber40 into the second plenum chamber 44 that allows for the gas-liquidstream to flow therethrough. As the gas-liquid stream is circulated asshown by the arrows 50, heavier liquid particles drop to the lowerportion 42 of the first plenum chamber 40. Additionally, heavier liquidparticles collect along the inner surface 110 of the housing 38 anddrain to the lower portion 42 of the first plenum chamber 40. Liquidthat collects in the lower portion 42 of the first plenum chamber 40thereafter drains from the housing 38 via the first drain port 64. Uponcompleting the cyclonic flow and separating heavier oil particles, flowexits directly through the chimney 96 into the impactor separator orcoalescer separator. The chimney 96 includes the second drain port 66,in the example shown comprising a tube 114 that extends down to the jetpump 26. The downstream end 100 of the chimney 96 is directly molded tothe main separator 43 (FIG. 2).

In the embodiment shown in FIGS. 2-5, the main separator 43 comprises animpactor separator comprising a nozzle plate 98 coupled to a downstreamend 100 of the chimney 96 and having a plurality of nozzles 102therethrough that accelerate the gas-liquid stream toward an impactionplate 104 downstream of the nozzle plate 98. This acceleration is shownby the arrows 54 in FIG. 3. in the embodiment shown, the main separator43 is a variable impactor separator that further comprises a valvecomprising a spring 150 and disc 152 assembled into a cup 153 with thenozzle plate 98 sonic welded, or in an alternative embodiment spinwelded, threaded in, glued, or the like, to the downstream end 100 ofthe chimney 96. In the configuration shown in FIG. 2, the spring 150 anddisc 152 are in a closed-disc valve configuration. However, when thepressure produced by flow through the chimney 96 is great enough toovercome the force of the spring 150, the disc 152 is unseated from thecup 153 and the gas-liquid stream flows into the cup 153 and thenthrough the nozzle plate 98. Different numbers and sizes of nozzles 102and different springs 150 may be used depending on the engine 12. Thevariable impactor separator and related components can be modified toaccommodate a variety of flow ranges, restriction, and efficiencyrequirements.

In the embodiment shown, a shroud 106 extends circumferentially anddownwardly from the impaction plate 104 and surrounds at least thedownstream end 100 of the chimney 96, The shroud 106 causes the gasstream to flow as shown by arrows 56. Liquid particles that areseparated by a sharp directional change in flow caused by the gas-liquidstream hitting the impaction plate 104 drip from the shroud 106 and fallto the lower portion 46 of the second plenum chamber 44. Separation withan impactor separator is described in U.S. Pat. No. 6,290,738, which wasincorporated by reference in its entirety herein above, and will thusnot be explained in more detail herein.

As shown in FIGS. 2, 3, and 6, the lower portion 46 of the second plenumchamber 44 comprises a funnel 108 that slopes downwardly from an innersurface 110 of the housing 38 to an external wall 112 of the chimney 96so as to drain liquid to the second drain port 66. In the embodimentshown, the second drain port 66 comprises a tube 114 extending from thelower portion 46 of the second plenum chamber 44, specifically from thelowest portion of the funnel 108, through the first plenum chamber 40 tothe jet pump 26. The tube 114 is hermetically sealed from the firstplenum chamber 40, such that the pressure in the first plenum chamber 40does not affect drainage of oil through the tube 114. In the embodimentshown herein, the tube 114 is coupled to the jet pump 26 via acylindrical projection 115 extending from the lower portion 42 of thefirst plenum chamber 40.

The gas-liquid separator 18 further comprises a conduit 68, FIG. 3,coupled to the housing 38 and in fluid communication with both the firstand second drain ports 64, 66 that conveys liquid from the lowerportions 42, 46 of the first and second plenum chambers 40, 44 away fromthe housing 38, as shown by arrows 60 and 62. In the embodiment shownherein, the conduit 68 comprises a pump that removes liquid from thelower portions 42, 46 of the first and second plenum chambers 40, 44through the first and second drain ports 64, 66, respectively. In oneembodiment, the pump comprises a jet pump 26 (see FIGS. 7-9) in fluidcommunication with both the first and second drain ports. 66 In theembodiment shown herein, the jet pump 26 is bolted to a lower portion140 of the housing 38 of the gas-liquid separator 18. Alternatively, thejet pump 26 could be integrally molded to the lower portion 140, FIGS. 2and 3, of the housing 38 of the gas-liquid separator 18 or coupled tothe housing in some other manner.

Now with reference to FIGS. 7-9, the jet pump 26 will be described inmore detail. As shown schematically in FIG. 9, a jet pump 26 is operatedby a motive fluid directed through a reduced diameter jet orifice 72into a larger diameter mixing bore 74 having a suction chamber 76 therearound. The momentum exchange between the high velocity motive jet flowfrom motive jet orifice 72 and the lower velocity surrounding fluid inmixing bore 74 creates a pumping effect which pumps fluid from suctionchamber 76, for example as shown in the flow diagram. Examples of jetpumps are described in “The Design of Jet Pumps”, Gustav Flugel,National Advisory Committee for Aeronautics, Technical Memorandum No.982, 1939; “Jet-Pump Theory and Performance with Fluids of HighViscosity”, R. G. Cunningham, Transactions of the ASME, November 1957,pages 1807-1820. In the embodiment of FIG. 9, jet pump 26 is afluid-driven jet pump having. a pressurized jet orifice at 72 receivingpressurized motive fluid from a source of pressurized fluid, such as oilpump 30, a suction chamber at 76 receiving separated oil from oil outlet24 of gas-liquid separator 18, and an output at mixing bore 74delivering jet-pumped oil to crankcase 14, as shown in FIG. 1.

Referring now to FIGS. 7 and 8, in the embodiment shown therein, the jetpump 26 comprises a first jet orifice 78 accelerating pressurized fluidso as to pump liquid from the first drain port 64 and a second jetorifice 80 accelerating pressurized fluid so as to pump liquid from thesecond drain port 66. First and second jet orifices 78, 80 correspond tojet orifice 72 shown in the schematic of FIG. 9. The jet pump 26 alsocomprises a feed bore 82 that supplies the pressurized fluid to both thefirst and second jet orifices 78, 80. The feed bore 82 is supplied withpressurized fluid via motive line 125 as shown in FIGS. 1 and 8, ormotive line 13$ as shown in FIG. 11. The jet pump 26 further comprises afirst suction port 84 that receives liquid from the first drain port 64and pressurized fluid from the first jet orifice 78, and a secondsuction port 86 that receives liquid from the second drain port 66 andpressurized fluid from the second jet orifice 80. Suction ports 84, 86correspond to suction chamber 76 in the schematic of FIG. 9. The jetpump 26 comprises a common mixing bore 88 that receives liquid from boththe first suction port 84 and the second suction port 86. Between thecommon mixing bore 8$ and the first and second. suction ports 84, 86,are intermediate mixing bores 90, 92, respectively. Mixing bores 88, 90.and 92 correspond to mixing bore 74 in the schematic of FIG. 9.

With continued reference to FIGS. 7 and 8, an assembly for removingscavenged liquid from a two-stage gas-liquid separator will bedescribed. The assembly comprises a first suction port 84 receivingscavenged liquid from a first stage, such as pre-separator 41, of thegas-liquid separator 18. The assembly comprises a second suction port 86receiving scavenged liquid from a second stage, such as a main separator43, of the gas-liquid separator 18. A first jet orifice 78 accelerates apressurized fluid into the first suction port 84. A second jet orifice80 accelerates the pressurized fluid into the second suction port 86. Afeed bore 82 supplies both the first and second jet orifices 78, 80 withthe pressurized fluid. A common mixing bore 88 receives the pressurizedfluid from the first and second jet orifices 78, 80 and receivesscavenged liquid from the first and second stages of the gas-liquidseparator. The assembly further comprises a first connection port 120conveying liquid from an outlet, such as first drain port 64 in thefirst stage of the gas-liquid separator 18 to the first suction port 84,and a second connection port 122 conveying liquid from an outlet, suchas second drain port 66 in the second stage of the gas-liquid separator18 to the second suction port 86. In the embodiment shown, the first andsecond suction ports 84, 86 extend perpendicularly to a flow of theaccelerated pressurized fluid flowing from the first and second jetorifices 78, 80, respectively. (See also FIG. 9) As shown in FIGS. 1 and8, the assembly can further comprise a drain line 124 coupled to themixing bore 88 that drains the scavenged liquid from the mixing bore 88to the crankcase 14 of the engine 12.

Now with reference to FIG. 10, a second embodiment of a gas-liquidseparator 18′ will be described. The gas-liquid separator 18′ comprisesan inlet 20 for receiving a gas-liquid stream and an outlet 22 fordischarging a gas stream. As in the first embodiment, the secondembodiment of the gas-liquid separator 18′ comprises a pre-separator 41that is a cyclone separator having an arched baffle 94 that guides thegas-liquid stream around the inner surface 110 of the housing 38 withinthe first plenum chamber 40. The gas-liquid stream is then directedupward through the chimney 96. Here, the gas-liquid stream is directedthrough a main separator 43, which in this embodiment is a coalescerseparator comprising a filter media 116 coupled to the downstream end100 of the chimney 96. Air flows in an inward-out (inside-out) directionthrough the filter media 116, as shown by the arrows 118. The filtermedia 116 has properties that cause oil to coalesce within/on the filtermedia 116 and thereby to separate from the gas-liquid stream.

While in the embodiment shown in FIG. 1 the pressurized fluid is oil, inthe embodiment shown in FIG. 11, the pressurized fluid is air. As shownin FIG. 11, the air is provided to the jet pump 26 via motive line 138.A turbocharger 126, in the example shown, fed with gas exiting, theoutlet 22 of the gas-liquid separator 18, provides the pressurized airto the jet pump 26 as shown by arrows 128. Alternatively, an aircompressor, for example as shown in dashed lines at 130, or a tank ofcompressed air, for example as shown in dashed lines at 132, can providethe pressurized air to the jet pump 26. One or more optional checkvalves 134, 136 can be provided in the motive line 138 and/or the drainline 124 to prevent backflow in a condition of low or negative airsupply pressure.

One result of the assembly described herein is an integrated productthat separates coarse liquid oil challenge before the main separator 43,for example with a pre-separator 41, such as a cyclone separator, whichcoarse liquid oil challenge is drained back to the engine 12 via a firstdrain port 64, in order to achieve high efficiency. The air-oil mixtureis then separated in a main separator 43, such as an impactor separator(FIG. 1) or a coalescer separator FIG. 10) and is drained via a seconddrain port 66 from the housing 38.

The jet pump 26 provides a way to drain the housing 38 from scavengedoil regardless of the pressure difference between a pressure in thefirst plenum chamber 40 and a pressure in the second plenum chamber 44.The two chambers 40, 44 are hermetically sealed from one anothereverywhere except for at nozzles 102. Hermetic seals are provided atfirst and second drain ports 64, 66 so as to prevent flow from leakingfrom the first plenum chamber 40, which is at a higher pressure, to thesecond plenum chamber 44, which is at a lower pressure, for example viathe second drain port 66. If flow leaked in this manner, it would not bepossible to drain the second plenum chamber 44 due to increased pressurein the second drain port 66. A high pressure due to oil build up fromthe second plenum chamber 44 is not required to overcome a pressurewithin the first plenum chamber 40 in order for the housing 38 to bedrained of scavenged oil because the jet pump 26 actively drains bothplenum chambers 40, 44 instead of relying on an oil column head toovercome the pressure difference. This eliminates the need for a checkvalve between the chambers 40, 44. This further eliminates the need todesign the gas-liquid separator 18 so as to limit pressure difference toenable a check valve to operate at certain engine conditions. This alsoallows the gas-liquid separator 18 to function in a wide range of engineconditions without concern for restriction affecting oil returncapability.

The jet orifices 78, 80 within the jet pump 26 can be fed off of asingle feed, such as through feed bore 82, and evacuated into a singledrain line 124, such as through common mixing bore 88. The high pressurefluid jetting through the first and second jet orifices 78, 80 allowsoil to be drained from the housing 38 independent of the pressure withinthe housing 38. Such drainage is independent of both the relativepressures between the pressure within the first and second plenumchambers 40,44 and independent, of the pressure within the crankcase 14.

Now referring to FIG. 12, in another example, a method for separating aliquid from a gas-liquid stream is provided. The method comprisesintroducing the gas-liquid stream into a housing 38 having a flowpaththerethrough from upstream to downstream, as shown at box 201. Themethod further comprises separating liquid from the gas-liquid stream ina first plenum chamber 40 defined by the housing 38, as shown at box202. The method further comprises draining liquid to a lower portion 42of the first plenum chamber 40 and through a first drain port 64, asshown at box 203. The method further comprises further separating liquidfrom the gas-liquid stream in a second plenum chamber 44 defined by thehousing 38 and downstream of the first plenum chamber 40, as shown atbox 204. The method further comprises draining liquid to a lower portion46 of the second plenum chamber 44 and through a second drain port 66,as shown at box 205. The method further comprises pumping liquid fromthe lower portions 42, 46 of the first and second plenum chambers 40, 44through the first and second drain ports 64, 66, respectively, as shownat box 206.

The method may further comprise pumping liquid from the first and seconddrain ports 64, 66 into first and second suction ports 84, 86,respectively. The method may further comprise accelerating pressurizedfluid through first and second jet orifices 78, 80 and into the firstand second suction ports 84, 86, respectively, so as to pump liquid fromthe lower portions 42, 46 of the first and second plenum chambers 40,44, respectively. The method may further comprise supplying thepressurized fluid to the first and second jet orifices 78, 80 from acommon pressurized fluid source. The method may further comprise mixingthe pressurized fluid from the first jet orifice 78 and the liquid fromthe first drain port 64 with the pressurized fluid from the second jetorifice 80 and the liquid from the second drain port 66 in a commonmixing bore 88. In one embodiment, as shown in FIG. 1, the pressurizedfluid is oil and the oil is provided from an oil pump 30 coupled to acrankcase 14. In another example, as shown in FIG. 11, the pressurizedfluid is air and the air is provided from a turbocharger 126.

In the above description certain terms have been used for brevity,clarity and understanding. No unnecessary limitations are to be inferredtherefrom beyond the requirement of the prior art because such terms areused fur descriptive purposes and are intended to be broadly construed.The different assemblies and methods described herein above may be usedalone or in combination with other assemblies and methods. Variousequivalents, alternatives and modifications are possible within thescope of the appended claims. Each limitation in the appended claims isintended to invoke interpretation under 35 USC §112(f) only if the terms“means for” or “step for” are explicitly recited in the respectivelimitation. While each of the method claims includes a specific seriesof steps for accomplishing certain functions, the scope of thisdisclosure is not intended to be bound by the literal order or literalcontent of steps described herein, and non-substantial differences orchanges still fall within the scope of the disclosure.

What is claimed is:
 1. A two-stage gas-liquid separator assemblycomprising: a housing haying a flowpath therethrough from upstream todownstream, the housing having an inlet, for receiving a gas-liquidstream and an outlet fur discharging a gas stream; a first plenumchamber defined by the housing and comprising a pre-separator thatcauses liquid to separate from the gas-liquid stream and to drain to alower portion of the first plenum chamber; a second plenum chamberdefined by the housing and comprising a main separator downstream of thepre-separator that further causes liquid to separate from the gas-liquidstream and to drain to a lower portion of the second plenum chamber; afirst drain port in the housing draining liquid from the lower portionof the first plenum chamber; and a second drain pot in the housingdraining liquid from the lower portion of the second plenum chamber;wherein liquid drains from the lower portions of the first and secondplenum chambers through the first and second drain ports, respectively,regardless of a pressure difference between a pressure in the firstplenum chamber and a pressure in the second plenum chamber.
 2. Theassembly of claim 1, further comprising a conduit in fluid communicationwith both the first and second drain ports that conveys liquid from thelower portions of the first and second plenum chambers away from thehousing.
 3. The assembly of claim 2, wherein the conduit comprises apump that removes liquid from the lower portions of the first and secondplenum chambers through the first and second drain ports, respectively.4. The assembly of claim 3, wherein the pump comprises a jet pump influid communication with both the first and second drain ports.
 5. Theassembly of claim 4, wherein the jet pump comprises a first jet orificeaccelerating pressurized fluid so as to pump liquid from the first drainport and a second jet orifice accelerating pressurized fluid so as topump liquid from the second drain port.
 6. The assembly of claim 5,wherein the pressurized fluid is oil.
 7. The assembly of claim 5,wherein the jet pump comprises a feed bore that supplies the pressurizedfluid to both the first and second jet orifices.
 8. The assembly ofclaim 7, wherein the jet pump comprises a first suction port thatreceives liquid from the first drain port and pressurized fluid from thefirst jet orifice, and a second suction port that receives liquid fromthe second drain port and pressurized fluid from the second jet orifice.9. The assembly of claim 8, wherein the jet pump comprises a mixing borethat receives liquid from both the first suction port and the secondsuction port.
 10. The assembly of claim 4, wherein the jet pump iscoupled to the housing.
 11. The assembly of claim 10, wherein the seconddrain port comprises a tube extending from the lower portion of thesecond plenum chamber through the first plenum chamber to the jet pump.12. The assembly of claim 1 further comprising a chimney supported bythe housing and extending from the first plenum chamber into the secondplenum chamber and allowing for the gas-liquid stream to flowtherethrough.
 13. The assembly of claim 12, wherein the lower portion ofthe second plenum chamber comprises a funnel that slopes downwardly froman inner surface of the housing to an external wall of the chimney so asto drain liquid to the second drain port.
 14. The assembly of claim 12,wherein the main separator is an impactor separator comprising a nozzleplate coupled to a downstream end of the chimney and haying a pluralityof nozzles therethrough that accelerate the gas-liquid stream toward animpaction plate downstream of the nozzle plate.
 15. The assembly ofclaim 14, further comprising a shroud extending circumferentially anddownwardly from the impaction plate and surrounding at least thedownstream end of the chimney.
 16. The assembly of claim 12, wherein themain separator is a coalescer separator comprising a filter mediacoupled to a downstream end of the chimney.
 17. The assembly of claim Iwherein the pre-separator is a cyclone separator.
 18. The assembly ofclaim 17, further comprising an arched baffle adjacent the inlet thatguides the gas-liquid stream along an inner surface of the first plenumchamber as the gas-liquid stream enters the first plenum chamber.
 19. Amethod for separating liquid from a gas-liquid stream, the methodcomprising: introducing the gas-liquid stream into a housing having aflowpath therethrough from upstream to downstream; separating, liquidfrom the gas-liquid stream in a first plenum chamber defined by thehousing; draining liquid to a lower portion of the first plenum chamberand through a first drain port; further separating liquid from thegas-liquid stream in a second plenum chamber defined by the housing anddownstream of the first plenum chamber; draining liquid to a lowerportion of the second plenum chamber and through a second drain port;and pumping liquid from the lower portions of the first and secondplenum chambers through the first and second drain ports, respectively.20. The method of claim 19, further comprising pumping liquid from thefirst and second drain ports into first and second suction ports,respectively.
 21. The method of claim 20, further comprisingaccelerating pressurized fluid through first and second jet orifices andinto the first and second suction ports, respectively, so as to pumpliquid from the lower portions of the first and second plenum chambers,respectively.
 22. The method of claim 21, further comprising supplyingthe pressurized fluid to the first and second jet orifices from a commonpressurized fluid source.
 23. The method of claim 22, further comprisingmixing the pressurized fluid from the first jet orifice and the liquidfrom the first drain port with the pressurized fluid from the second jetorifice and the liquid horn the second drain port in a common mixingchamber.
 24. The assembly of claim 21, wherein the pressurized fluid isoil.
 25. The assembly of claim 24, wherein the oil is provided from anoil pump coupled to a crankcase of an engine.
 26. The assembly of claim21, wherein the pressurized, fluid is air.
 27. The assembly of claim 26,wherein the air is provided from a turbocharger.
 28. An assembly forremoving scavenged liquid from a two-stage gas-liquid separator, theassembly comprising: a first suction port receiving scavenged liquidfrom a first stage of the gas-liquid separator; a second suction portreceiving scavenged liquid from a second stage of the gas-liquidseparator; a first jet orifice accelerating a pressurized fluid into thefirst suction port; a second jet orifice accelerating the pressurizedfluid into the second suction port; a feed bore supplying both the firstand second jet orifices with the pressurized fluid, and a common mixingbore receiving the pressurized fluid from the first and second jetorifices and receiving scavenged liquid from the first and second stagesof the gas-liquid separator.
 29. The assembly of claim 28, furthercomprising a first connection port conveying liquid from an outlet inthe first stage of the gas-liquid separator to the first suction port,and a second connection port conveying liquid from an outlet in thesecond stage of the gas-liquid separator to the second suction port. 30.The assembly of claim 28, wherein the first and second suction portsextend perpendicularly to a flow of the accelerated, pressurized fluidfrom the first and second jet orifices, respectively.
 31. The assemblyof claim 28, further comprising a drain line coupled to the commonmixing bore that drains the scavenged liquid from the common mixing boreto a crankcase of an engine.
 32. The assembly of claim 28, wherein thepressurized fluid is oil.
 33. The assembly of claim 28, wherein thepressurized fluid is air.
 34. The assembly of claim 28, wherein theassembly is integrally molded to a lower portion of a housing of thegas-liquid separator.
 35. The assembly of claim 28, wherein the assemblyis bolted to a lower portion of a housing of the gas-liquid separator.